Thanks to the Hubble Space Telescope, astronomers have caught a rare display of auroras on Uranus, which ranks among the solar system's oddest planets.Unlike the beautiful, rippling curtains of greenish light we've been seeing in earthly skies over the past few months, the Urani …

Laurent LamyThese composite images show Uranian auroras as bright spots on the planet's disk on Nov 16, 2011 (left), and on Nov. 29 (right). The images from the Hubble Space Telescope have been processed to bring out details in Uranus' faint ring system.By Alan Boyle

Follow @b0yleThanks to the Hubble Space Telescope, astronomers have caught a rare display of auroras on Uranus, which ranks among the solar system's oddest planets.Unlike the beautiful, rippling curtains of greenish light we've been seeing in earthly skies over the past few months, the Uranian auroras are short-lived bright spots sitting on top of the ice giant's bluish cloud tops. But they're caused by a similar mechanism, involving the interaction of electrically charged particles with atoms and ions in the planet's upper atmosphere.NASA's Voyager 2 probe picked up the first evidence of Uranus' auroras in 1986. "Since then, we've had no opportunities to get new observations ...